Showing papers by "Hewlett-Packard published in 1972"

Polyphase codes with good periodic correlation properties (Corresp.)

Abstract: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags. There is no restriction on code lengths.

General purpose calculator with capability for performing interdisciplinary business calculations

Abstract: A battery-powered, hand-held, calculator employs MOS/LSI calculator circuits to perform arithmetic and financial calculations. Data and commands are input to the calculator from a keyboard having a prefix key to double the functions of selected keys. A 15-digit, seven-segment light emitter diode (LED) display serves as the output for the calculator. The calculator circuits include a read-only memory circuit in which the algorithms for performing the arithmetic and financial calculations are stored; a control and timing circuit for scanning the keyboard, retaining status information about the condition of the calculator or of an algorithm, and generating the next read-only memory address; and an arithmetic and register circuit containing an adder, a group of working registers, a group of data storage registers forming a stack for roll down operation, and a constant storage register. These circuits are interconnected by a multiple line buss system.

Cross modulation and intermodulation in amplifiers at high frequencies

Abstract: Cross modulation and intermodulation in amplifiers at high frequencies are investigated using the Volterra series approach. The general relationships between these forms of distortion are defined and the importance of phase in the specification of cross modulation is discussed. The use of feedback for distortion at high frequencies is investigated and it is shown that appropriate control of the feedback loop phase shift can result in substantial reductions in cross modulation over broad bandwidths. All theoretical conclusions are verified by circuit measurements at frequencies up to 200 MHz.

Liquid phase epitaxial growth of Ga x In 1-x P

Abstract: Single crystal epitaxial layers of Gaxln1−xP alloys have been grown by the steady-state liquid phase epitaxial growth technique on (111)B GaAs substrates. The crystal growth process has been studied in detail and the resultant epitaxial layers have been characterized with respect to their structural, electrical and optical properties. Epitaxial layers of good structural quality could be grown only in the composition range x = 0.48 to 0.53, where the lattice parameter is close to that of the GaAs substrate. The band gap of these crystals was in the range 1.86 – 1.92 eV as determined by optical absorption and photoluminescence measurements.

The growth and properties of LPE GaAs

Abstract: Air leaks in the growth apparatus and impurities in the source material are the major sources of charged defect centers in LPE GaAs grown in rotary reactors from Ga solutions With perfected apparatus and purified source material the residual acceptor concentration in n -type layers is routinely 10 14 cm −3 or less Doping with Sn and Ge is studied and characterized by donor-acceptor partition ratios and segregation coefficients Theory and experiment are compared for the dependence of the mobility of electrons and holes on concentration at 77°K and 300°K for 3 × 10 13 cm −3 ⩾ n ⩾ 3 × 10 16 cm −3 and 10 15 cm −3 ⩽ p ⩽ 10 19 cm −3 Thickness and doping uniformity and reproducibility and surface morphology are characterized

Bus oriented,modular,multiprocessing computer

Abstract: A multiprocessing computer is structured in modular form around a common control and data bus. Control functions for the various modules are distributed among the modules to facilitate system flexibility. Modules separate from the central processor handle input/output operations to free the central processor for data manipulation. The central processor includes circuitry for instruction and data pipelining, single, double and triple shifts, preadding and memory mapping and interleaving. The central processor also includes a read only memory look-up table for microprogramming instructions.

Materials for light emitting diodes

Abstract: III–V semiconductor display diodes fall into three material categories: direct, indirect, and diode-phosphor combinations. The light generation mechanisms are well understood in each case. On the basis of the luminous efficacy achieved in the laboratory, the merit of the various materials is in the order: GaP: N (green), GaP: Zn, O (red), GaInP (yellow), GaAsP (red), GaAlAs (red) and GaAs-phosphor combinations (red, green, blue). A more comprehensive assessment of quality must take into account factors such as the economic feasibility of the methods of synthesis, the applicability to monolithic arrays, and the suitability of spectra (hue, contrast, saturation, etc.). The degree of importance of these matters and the limitations of the various materials are less well-defined at present. New developments which may have an impact on the future of display diodes include the use of AlxGa1-xP in place of GaP to shift spectra to shorter wavelengths, the possible development of very bright direct alloys of InP with either GaP or A1P, and the doping of GaAsP with N to extend its range of colors.

Interferometer system for measuring straightness and roll

Abstract: An interferometer system for measuring straightness including a light source for producing a beam of light, preferably a two frequency laser with the two frequency components linearly polarized and orthogonal to one another, the light beam being directed through a Wollaston prism where the beam is split into two separate paths which deviate, in opposite paths, from the original beam direction by a small angle. The two separate beams are transmitted over two separate paths to associated ones of two separate reflective surfaces which are mounted in a mutually fixed relationship and at an angle to each other. The two beams are reflected back into the prism from the associated reflective surfaces where they are recombined. Photodetector means are provided for detecting any changes in the fringes resulting from a change in one optical path length relative to other optical path length as the two mirrors move relative to the prism, said change in path lengths resulting from deviations from straightness in such movement. A dual system is disclosed for measuring rotational motion, i.e., roll.

Phase lock loop for locking on highest amplitude signal

Abstract: A broadband, limiting amplifier is used in the IF portion of a harmonic phase lock loop, preceding the IF bandpass filter. The limiting amplifier gives an output signal of a predetermined magnitude having a frequency corresponding to the input signal having the highest level, and a detector connected to the output of the IF bandpass filter inhibits the phase lock loop whenever the signal passing through the bandpass filter is below the predetermined magnitude.

Transducer formed in peripherally supported thin semiconductor web

Abstract: A thin web supported by a peripheral frame is formed from a single crystal of silicon, the web and frame being of opposite conductivity types. A lower resistivity region is diffused into the web, and the web is covered by an insulating layer having holes through which conductors are deposited in contact with each end of the diffused region. The resulting transducer can be used as a thermocouple or strain gage. For use as a thermocouple, one of the junctions between the diffused region and a conductor is situated near the center portion of the web. The diffused region comprises one leg of the thermocouple, and one of the conductors functions as the other leg. The frame acts as a heat sink relative to the center portion of the web, making the junction near the center portion a hot junction and the junction near the frame a cold junction. For use as a diaphragm type strain gage the diffused region is made to transverse most of the web. The frame serves as a mounting base that is integral with the strain gage. The resistance of the diffused region changes in proportion to the change of the dimensions of the diffused region that result from the application of a force normal to the plane of the web.

Method for achieving uniform exposure in a photosensitive material on a semiconductor wafer

Abstract: A method of fabricating semiconductor devices on a wafer, in which an antireflection layer is interposed between a layer of insulating material and a photosensitive layer. The use of this antireflection layer allows suppression of the optical interference between an incident light wave and a light wave that is ordinarily reflected back into the photosensitive layer. Also, this layer provides a surface to which a positive photoresist material generally used as the photosensitive layer will adhere tenaciously.

Microwave YIG-tuned transistor oscillator amplifier design: application to C band

Abstract: An approach to the design of a microwave YIG-tuned transistor oscillator amplifier is discussed in this paper. A classic lumped-element model of the transistor is used to show that a simple but still accurate equivalent circuit can be useful in predicting the effect of transistor parameters on the tuning range of a microwave oscillator. On the other hand, this paper describes a design procedure `without model' based on the small-signal characterization of the transistor by its scattering matrix. This method is particularly suited to amplifier designing since scattering parameters are inherently power-flow parameters and well adapted to computer-aided design (CAD) and optimization techniques. A 3.0-6.5 GHz YIG-tuned transistor oscillator amplifier with 10 mW of output power illustrates the usefulness of these two methods.

Crystal monochromator and method of fabricating a diffraction crystal employed therein

Abstract: A crystalline quartz disc capable of diffracting X-radiation at a Bragg angle in the range from fifty to ninety degrees is formed with flat surfaces parallel to its atomic planes. This disc is forced against a spherical surface of a quartz substrate and brazed in place to provide a spherical diffraction crystal with a radius of curvature equal to the diameter of the Rowland circle. A monochromator is provided in which this spherical diffraction crystal monochromatically focuses X-radiation from a source at a point on the Rowland circle onto a target at a conjugate point on the Rowland circle.

Bent diffraction crystal with geometrical aberration compensation

Abstract: A spherically bent diffraction crystal employed in an X-ray monochromator is provided with a nonuniform strain distribution to compensate for a geometrical aberration produced by nonconformity of the surface of the diffraction crystal to the Rowland circle of the monochromator.

Cable fastener for electrocardiograph electrodes

Abstract: A cable fastener provides an electrically conducting mechanical connection between a standard male snap fastener commonly used as an electrocardiograph electrode and a cable. The male snap fastener is positively held in contact with the cable fastener by a spring.

Schottky barrier infrared detector having ultrathin metal layer

Abstract: A metal film less than 100 Angstroms thick is deposited on one face of a semiconductor substrate to form a Schottky-barrier diode. Photons absorbed in the metal form electron-hole pairs; and those carriers with sufficient energy, in the right direction to cross the Schottky barrier, cause a current which is proportional to the incident radiant flux.

GaAs microwave Schottky-gate FET

Abstract: A GaAs FET transistor with 0.9μm Schottky barrier gate that exhibits an extrapolated maximum frequency of oscillation of 40 GHz has been developed. Coupling of the transistor to coplanar waveguides has been accomplished with negligible parasitic reactances.

Connector for printed circuit boards

Abstract: A connector for providing mechanical support and electrical contact between two printed circuit boards, or between an electrical component and a printed circuit board includes a base, two contact members, and a guide tip. A plurality of the connectors may be aligned by one or more removable tabs until assembly or encapsulation.

Comments and experimental results on optimal digital ladder structures

Abstract: Features of an optimal digital ladder structure are analyzed in an example. Comparisons are made with a suboptimal digital ladder structure and a cascade structure.

Multiemitter coupled logic gate

Abstract: The emitters and bases of two transistors, at least one of which has more than one emitter, are used as inputs, while the collectors and emitters are used as outputs. The collector of the first transistor is connected to the base of the second transistor. The collectors of both transistors are electrically biased. A resistor is connected between the bias source and the collector of the first transistor. A third transistor, connected as a diode, clamps the voltage across the resistor to a selected value even if more than one input to the first transistor is low. With changes in inputs and outputs, the circuit can function as a basic AND-OR gate, a trigger circuit for pulse shaping, an R-S latch, and a gated latch. By combination of basic gates, more complex logic functions can be achieved.

Scanning light emitting diode display of digital information

Abstract: A digital logic display in which a row of light emitting diodes (LED''s) is used to indicate the logic state of each bit of a sequence of bits present at one input. Another row of light emitting diodes is used in one mode to indicate the logic state of each bit of a sequence of bits present at another input, and in another mode to indicate the logic state of each bit of a sequence of bits that result from performing a pre-selected Boolean operation on corresponding bits of the two input sequences. By means of associated digital circuitry, the original input bit sequences are broken up into shorter sequences which are cycled in closed loops in a series of shift registers, thereby preserving the original data intact while sampled bits are subjected to preselected Boolean operations. Also this procedure facilitates the use of a scanning mechanism whereby each output LED is responsive to the logic state of selected bits only periodically.

Growth of rare earth orthoferrites and garnets using BaO-based solvents

Abstract: A new solvent, comprised of BaO,B2O3, and BaF2 has been developed for the growth of orthoferrites and the magnetically uniaxial rare earth iron garnets. This solvent has several advantages over the conventional PbO-based solvents, including significantly lower vapor pressure and lower chemical reactivity with Pt. Salient features of the relevant phase equilibria have been experimentally determined. The BaO-based solvent has been used for bulk, homoepitaxial, and heteroepitaxial growth of orthoferrites and garnets in the temperature range of 900° – 1300°C. In the case of heteroepitaxial growth, non-magnetic substrates such as Gd3Ga5O12 have been employed. Characterization of the resulting material by a number of physical and chemical measurements indicates properties comparable to, and in some cases superior to, those reported for crystals grown from PbO-based solvents.